<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html><head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Obtaining SQL Function Parameter Values</title>
<style type="text/css">
body {
    margin: auto;
    font-family: Verdana, sans-serif;
    padding: 8px 1%;
}

a { color: #044a64 }
a:visited { color: #734559 }

.logo { position:absolute; margin:3px; }
.tagline {
  float:right;
  text-align:right;
  font-style:italic;
  width:300px;
  margin:12px;
  margin-top:58px;
}

.toolbar {
  text-align: center;
  line-height: 1.6em;
  margin: 0;
  padding: 0px 8px;
}
.toolbar a { color: white; text-decoration: none; padding: 6px 12px; }
.toolbar a:visited { color: white; }
.toolbar a:hover { color: #044a64; background: white; }

.content    { margin: 5%; }
.content dt { font-weight:bold; }
.content dd { margin-bottom: 25px; margin-left:20%; }
.content ul { padding:0px; padding-left: 15px; margin:0px; }

/* rounded corners */
.se  { background: url(../images/se.gif) 100% 100% no-repeat #044a64}
.sw  { background: url(../images/sw.gif) 0% 100% no-repeat }
.ne  { background: url(../images/ne.gif) 100% 0% no-repeat }
.nw  { background: url(../images/nw.gif) 0% 0% no-repeat }

/* Things for "fancyformat" documents start here. */
.fancy img+p {font-style:italic}
.fancy .codeblock i { color: darkblue; }
.fancy h1,.fancy h2,.fancy h3,.fancy h4 {font-weight:normal;color:#044a64}
.fancy h2 { margin-left: 10px }
.fancy h3 { margin-left: 20px }
.fancy h4 { margin-left: 30px }
.fancy th {white-space:nowrap;text-align:left;border-bottom:solid 1px #444}
.fancy th, .fancy td {padding: 0.2em 1ex; vertical-align:top}
.fancy #toc a        { color: darkblue ; text-decoration: none }
.fancy .todo         { color: #AA3333 ; font-style : italic }
.fancy .todo:before  { content: 'TODO:' }
.fancy p.todo        { border: solid #AA3333 1px; padding: 1ex }
.fancy img { display:block; }
.fancy :link:hover, .fancy :visited:hover { background: wheat }
.fancy p,.fancy ul,.fancy ol { margin: 1em 5ex }
.fancy li p { margin: 1em 0 }
/* End of "fancyformat" specific rules. */

</style>
  
</head>
<body>
<div><!-- container div to satisfy validator -->

<a href="../index.html">
<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite Logo"
 border="0"></a>
<div><!-- IE hack to prevent disappearing logo--></div>
<div class="tagline">Small. Fast. Reliable.<br>Choose any three.</div>

<table width=100% style="clear:both"><tr><td>
  <div class="se"><div class="sw"><div class="ne"><div class="nw">
  <table width=100% style="padding:0;margin:0;cell-spacing:0"><tr>
  <td width=100%>
  <div class="toolbar">
    <a href="../about.html">About</a>
    <a href="../sitemap.html">Sitemap</a>
    <a href="../docs.html">Documentation</a>
    <a href="../download.html">Download</a>
    <a href="../copyright.html">License</a>
    <a href="../news.html">News</a>
    <a href="../support.html">Support</a>
  </div>
<script>
  gMsg = "Search SQLite Docs..."
  function entersearch() {
    var q = document.getElementById("q");
    if( q.value == gMsg ) { q.value = "" }
    q.style.color = "black"
    q.style.fontStyle = "normal"
  }
  function leavesearch() {
    var q = document.getElementById("q");
    if( q.value == "" ) { 
      q.value = gMsg
      q.style.color = "#044a64"
      q.style.fontStyle = "italic"
    }
  }
</script>
<td>
    <div style="padding:0 1em 0px 0;white-space:nowrap">
    <form name=f method="GET" action="http://www.sqlite.org/search">
      <input id=q name=q type=text
       onfocus="entersearch()" onblur="leavesearch()" style="width:24ex;padding:1px 1ex; border:solid white 1px; font-size:0.9em ; font-style:italic;color:#044a64;" value="Search SQLite Docs...">
      <input type=submit value="Go" style="border:solid white 1px;background-color:#044a64;color:white;font-size:0.9em;padding:0 1ex">
    </form>
    </div>
  </table>
</div></div></div></div>
</td></tr></table>
<div class=startsearch></div>
  
<a href="intro.html"><h2>SQLite C Interface</h2></a><h2>Obtaining SQL Function Parameter Values</h2><blockquote><pre>const void *sqlite3_value_blob(sqlite3_value*);
int sqlite3_value_bytes(sqlite3_value*);
int sqlite3_value_bytes16(sqlite3_value*);
double sqlite3_value_double(sqlite3_value*);
int sqlite3_value_int(sqlite3_value*);
sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
const unsigned char *sqlite3_value_text(sqlite3_value*);
const void *sqlite3_value_text16(sqlite3_value*);
const void *sqlite3_value_text16le(sqlite3_value*);
const void *sqlite3_value_text16be(sqlite3_value*);
int sqlite3_value_type(sqlite3_value*);
int sqlite3_value_numeric_type(sqlite3_value*);
</pre></blockquote><p>
The C-language implementation of SQL functions and aggregates uses
this set of interface routines to access the parameter values on
the function or aggregate.</p>

<p>The xFunc (for scalar functions) or xStep (for aggregates) parameters
to <a href="../c3ref/create_function.html">sqlite3_create_function()</a> and <a href="../c3ref/create_function.html">sqlite3_create_function16()</a>
define callbacks that implement the SQL functions and aggregates.
The 3rd parameter to these callbacks is an array of pointers to
<a href="../c3ref/value.html">protected sqlite3_value</a> objects.  There is one <a href="../c3ref/value.html">sqlite3_value</a> object for
each parameter to the SQL function.  These routines are used to
extract values from the <a href="../c3ref/value.html">sqlite3_value</a> objects.</p>

<p>These routines work only with <a href="../c3ref/value.html">protected sqlite3_value</a> objects.
Any attempt to use these routines on an <a href="../c3ref/value.html">unprotected sqlite3_value</a>
object results in undefined behavior.</p>

<p>These routines work just like the corresponding <a href="../c3ref/column_blob.html">column access functions</a>
except that  these routines take a single <a href="../c3ref/value.html">protected sqlite3_value</a> object
pointer instead of a <a href="../c3ref/stmt.html">sqlite3_stmt*</a> pointer and an integer column number.</p>

<p>The sqlite3_value_text16() interface extracts a UTF-16 string
in the native byte-order of the host machine.  The
sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
extract UTF-16 strings as big-endian and little-endian respectively.</p>

<p>The sqlite3_value_numeric_type() interface attempts to apply
numeric affinity to the value.  This means that an attempt is
made to convert the value to an integer or floating point.  If
such a conversion is possible without loss of information (in other
words, if the value is a string that looks like a number)
then the conversion is performed.  Otherwise no conversion occurs.
The <a href="../c3ref/c_blob.html">datatype</a> after conversion is returned.</p>

<p>Please pay particular attention to the fact that the pointer returned
from <a href="../c3ref/value_blob.html">sqlite3_value_blob()</a>, <a href="../c3ref/value_blob.html">sqlite3_value_text()</a>, or
<a href="../c3ref/value_blob.html">sqlite3_value_text16()</a> can be invalidated by a subsequent call to
<a href="../c3ref/value_blob.html">sqlite3_value_bytes()</a>, <a href="../c3ref/value_blob.html">sqlite3_value_bytes16()</a>, <a href="../c3ref/value_blob.html">sqlite3_value_text()</a>,
or <a href="../c3ref/value_blob.html">sqlite3_value_text16()</a>.</p>

<p>These routines must be called from the same thread as
the SQL function that supplied the <a href="../c3ref/value.html">sqlite3_value*</a> parameters.
</p><p>See also lists of
  <a href="objlist.html">Objects</a>,
  <a href="constlist.html">Constants</a>, and
  <a href="funclist.html">Functions</a>.</p>
